Injection bolts having a static mixer are known, for example, from DE 100 17 750 A1. These injection bolts are used primarily as rock bolts for stabilising rock mass in mines in the vicinity of galleries and drifts or in stabilising a roof of a tunnel. Such an injection bolt has a shaft with an internal bore which contains the static mixer. The injection bolt generally also has a pump connector and the shaft has an outlet.
Known injection bolts are used to stabilise a rock mass as follows. Firstly, a drill bolt is used to drill a hole into the rock mass. After a suitably deep hole has been drilled, this bolt is exchanged for an injection bolt. A pump is then connected to the injection bolt's pump connector. The pump is then used to inject a multiple component anchoring material into the internal bore of injection bolt. The components of the anchoring material are mixed by the static mixer in such a way that the multiple components jointly cure very quickly once they have been ejected from the outlet of the injection bolt into the annular channel between the shaft and the rock mass. The anchoring material fills said channel and also any slots and cleat planes in the rock mass. The bolt shaft then remains in the hole and helps, in addition to the anchoring material, to secure the walls of a mined cavity.
According to an alternative method, the injection bolt may also be used in the first step as a drill bolt if it is arranged such that a drill head can be associated therewith. As this injection bolt will remain in the hole, the drill head must be inexpensive. Generally such an injection bolt will only be use in specific applications.
In order to achieve the correct mixing effect, it is generally desired to construct and arrange the static mixer in such a way that the mixed anchoring components do not have to cover a long distance before reaching the channel. This is because the longer the distance they have to cover, the greater the risk that they will cure before they reach the channel. A further requirement is that the static mixer is arranged such that the anchoring components are mixed intensively with one another.
It is therefore desirable to prevent the static mixer from issuing with the injected-in multiple anchoring components at the outlet or from leaving its predetermined position, i.e. from slipping downward in the bore of the shaft of the injection bolt.
It is also known for the multiple anchoring components to be introduced into the injection bolt while embedded in film tubes. In use, the multiple anchoring components are pressed through the static mixer. Conventional static mixers have a multistage coil formed from a plastics material with means for restricted flow diversion, such that an appropriate pressure has to be applied to purposefully press the components of the anchoring material through the static mixer. The static mixer therefore has a crucial role which it is able to realise and fulfil only if it is positioned precisely and if it is able to maintain this positioning throughout the entire operation despite the high pressure of the mortar.
The object of the invention is therefore to provide a method for producing injection bolts in which the static mixer is precisely positioned at all times and an injection bolt having a fixed static mixer, via which thorough mixing and immediate introduction of a quick-cure anchoring material are possible.